zig libc: exp10, exp10f, pow10, pow10f (#31163)

See #30978.

Commands i run:
```
$ stage3/bin/zig build -p stage4 -Denable-llvm -Dno-lib

$ stage4/bin/zig build test-libc -Dlibc-test-path=../../libc-test -Dtest-filter=exp10 -fqemu -fwasmtime --summary line
Build Summary: 725/737 steps succeeded (12 skipped)
```

Reviewed-on: https://codeberg.org/ziglang/zig/pulls/31163
Reviewed-by: Andrew Kelley <andrew@ziglang.org>
Co-authored-by: Pivok <pivoc@protonmail.com>
Co-committed-by: Pivok <pivoc@protonmail.com>

lib/c/math.zig

@@ -45,8 +45,12 @@ comptime {
         symbol(&atanl, "atanl");
         symbol(&cbrt, "cbrt");
         symbol(&cbrtf, "cbrtf");
+        symbol(&exp10, "exp10");
+        symbol(&exp10f, "exp10f");
         symbol(&hypot, "hypot");
         symbol(&pow, "pow");
+        symbol(&pow10, "pow10");
+        symbol(&pow10f, "pow10f");
     }
 
     if (builtin.target.isMuslLibC()) {
@@ -123,6 +127,14 @@ fn cbrtf(x: f32) callconv(.c) f32 {
     return math.cbrt(x);
 }
 
+fn exp10(x: f64) callconv(.c) f64 {
+    return math.pow(f64, 10.0, x);
+}
+
+fn exp10f(x: f32) callconv(.c) f32 {
+    return math.pow(f32, 10.0, x);
+}
+
 fn hypot(x: f64, y: f64) callconv(.c) f64 {
     return math.hypot(x, y);
 }
@@ -138,3 +150,11 @@ fn hypotl(x: c_longdouble, y: c_longdouble) callconv(.c) c_longdouble {
 fn pow(x: f64, y: f64) callconv(.c) f64 {
     return math.pow(f64, x, y);
 }
+
+fn pow10(x: f64) callconv(.c) f64 {
+    return exp10(x);
+}
+
+fn pow10f(x: f32) callconv(.c) f32 {
+    return exp10f(x);
+}

lib/libc/musl/src/math/exp10.c

@@ -1,24 +0,0 @@
-#define _GNU_SOURCE
-#include <math.h>
-#include <stdint.h>
-
-double exp10(double x)
-{
-	static const double p10[] = {
-		1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10,
-		1e-9, 1e-8, 1e-7, 1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1,
-		1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
-		1e10, 1e11, 1e12, 1e13, 1e14, 1e15
-	};
-	double n, y = modf(x, &n);
-	union {double f; uint64_t i;} u = {n};
-	/* fabs(n) < 16 without raising invalid on nan */
-	if ((u.i>>52 & 0x7ff) < 0x3ff+4) {
-		if (!y) return p10[(int)n+15];
-		y = exp2(3.32192809488736234787031942948939 * y);
-		return y * p10[(int)n+15];
-	}
-	return pow(10.0, x);
-}
-
-weak_alias(exp10, pow10);

lib/libc/musl/src/math/exp10f.c

@@ -1,22 +0,0 @@
-#define _GNU_SOURCE
-#include <math.h>
-#include <stdint.h>
-
-float exp10f(float x)
-{
-	static const float p10[] = {
-		1e-7f, 1e-6f, 1e-5f, 1e-4f, 1e-3f, 1e-2f, 1e-1f,
-		1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7
-	};
-	float n, y = modff(x, &n);
-	union {float f; uint32_t i;} u = {n};
-	/* fabsf(n) < 8 without raising invalid on nan */
-	if ((u.i>>23 & 0xff) < 0x7f+3) {
-		if (!y) return p10[(int)n+7];
-		y = exp2f(3.32192809488736234787031942948939f * y);
-		return y * p10[(int)n+7];
-	}
-	return exp2(3.32192809488736234787031942948939 * x);
-}
-
-weak_alias(exp10f, pow10f);

src/libs/musl.zig

@@ -848,8 +848,6 @@ const src_files = [_][]const u8{
     "musl/src/math/erf.c",
     "musl/src/math/erff.c",
     "musl/src/math/erfl.c",
-    "musl/src/math/exp10.c",
-    "musl/src/math/exp10f.c",
     "musl/src/math/exp10l.c",
     "musl/src/math/exp2f_data.c",
     "musl/src/math/exp2l.c",

src/libs/wasi_libc.zig

@@ -710,8 +710,6 @@ const libc_top_half_src_files = [_][]const u8{
     "musl/src/math/erf.c",
     "musl/src/math/erff.c",
     "musl/src/math/erfl.c",
-    "musl/src/math/exp10.c",
-    "musl/src/math/exp10f.c",
     "musl/src/math/exp10l.c",
     "musl/src/math/exp2f_data.c",
     "musl/src/math/exp2l.c",