Remove unnecessary functions from jsmath.c. NFC

[sbc100]

See the comments at the top of emscripten/js_math.h for why JS versions of these functions are not needed.

As a followup I plan to map jsmath.c functions to em_math.h functions instead of using EM_JS here.

See #19284

[sbc100]

See

emscripten/system/include/emscripten/em_math.h

Lines 25 to 36 in 1171ada

	// The following operations have very fast WebAssembly opcodes. Therefore they are not
	// exposed as individual functions:
	// Math.abs(x) -> f32.abs and f64.abs. (use fabsf() and fabs() from math.h)
	// Math.ceil -> f32.ceil and f64.ceil (ceil() and ceilf() in math.h)
	// Math.clz32(x) -> i32.clz and i64.clz (call __builtin_clz() and __builtin_clzll())
	// Math.floor -> f32.floor and f64.floor (floor() and floorf() in math.h)
	// Math.fround -> f64.promote_f32(f32.demote_f64()) (call double d = (double)(float)someDouble;)
	// Math.imul(x, y) -> i32.mul and i64.mul (directly multiply two signed integers)
	// Math.min -> f32.min and f64.min (fminf() and fmin() in math.h)
	// Math.max -> f32.max and f64.max (fmaxf() and fmax() in math.h)
	// Math.trunc -> f32.trunc and f64.trunc (truncf() and trunc() in math.h)

[sbc100]

These two are already implement in musl in terms of rint and rintf